(The Arroyo Del Valle Creek Project)
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Froggy Facts
Introduction
There are a great deal of critters that inhabit the Arroyo Del Valle, but among the thousands of occupants, we chose frogs for our research project. Frogs are very interesting
creatures, and they are also very bizarre. However, before we can learn about that, we must first learn what a frog is. First off, all frogs are called by scientists, Anuras. (Latin for
"Tailless.") A frog is an Amphibian, which translates roughly from Latin meaning "Double Life," and this name suites the frog very well, (as you will see later.) Amphibians differ
from other animals such as dogs or fish or snails, in that they have no fur, scales, or shells of any kind. They do not give birth to their young inside the mother, which is unlike human
birth, however they still use sexual reproduction which will be explained later as well. They are also cold blooded, and their level of activity is directly related to the temperature:
they are more active as it gets hotter. Frogs have also gained bad reputations. For example, in the middle ages, people thought that frogs fell from the sky, and that you could get
warts by touching them, (lies,) and a select few even thought that if you caught and continued to seduce and kiss the correct frog, it might turn into a prince. This is also just another
wives tale. Still, some people still think that you can get warts from touching a frog that has wart-like skin.
Background Information
Toads are often mistaken for frogs, and they have some similarities. A toad is an amphibian, just not the same species as a frog. However, there a some very important differences
between frogs and toads, and they are as follows: frogs jump, they can have a slimy\slippery feel to them, and generally they are moist and wet. Toads on the other hand walk
around slowly, have wart-like skin, are dry and can retain water much longer than the conventional frog, allowing it to leave areas that are committed to moisture, and great deals of
humidity. Also frogs in general have longer rear legs than front legs (used for jumping and swimming because of their inability to retain moisture for more than a few hours, forcing
them to live in a habitat that has water readily available,) as opposed to toads, who have longer front legs than rear legs used for walking, and stalking their prey. (No long legs
needed for swimming, because they are capable of living less aquatic areas.) We found two very distinct species of frogs living in our Arroyo Del Valle, they are the Green Frog,
and the Bull frog. (Both belonging to the family Ranidae,) These two species interact with each other daily in many ways. First of all, they share a habitat, (The Arroyo Del Valle,)
and they are also found in any lake, pond, or slow moving river or stream. Secondly, they share a food supply, (small insects, small birds, field mice, tiny reptiles, and even other
species of frogs! -Tadpoles dine on luscious algae.) which are also found in the same habitat. Finally, they share predators, like the kingfisher.
The process of getting the opposite sex's attention differs from that of convention normalities that the human race provides; in froggy land the typical way to get the attention of the
other sex is to croak, (males do this to attract females, it is called a mating call). Different species have different mating calls. You have probably heard a frog somewhere in the
bushes out side of your house at 4 A.M. and it would not stop. That was just a lonely male frog, looking for some lady frogs to hang out with. The different tones heard from these
calls vary because depending on the frogs size, the volume will increase or decrease. A male frog will pump air back and forth between his lungs and his mouth, across his vocal
cords, causing a resignation that is heard as not a croak, but a mating call. (calls vary from species to species.) It is almost like blowing over the top of an empty glass bottle of
Coca Cola. Occasionally, and in the case of the bull and green frog, the males will have a vocal sac under their chin, looking much like an iguana's dewlap, which inflate with air
causing deeper resignation and even louder mating calls. The bullfrog's mating call is the traditional "Jug-o-rum" call, while the Green Frog's call is a "tung" type of sound. These
noises are often heard at different pitches, indicating different frogs. They are also repeated very much, so as to increase their chances that a female will hear them. After the male
finally attracts his mate, and fertilizes the eggs, the eggs are released into still water, or suspended above still water, so that the tadpoles will be able to survive after hatching. The
tadpoles hatch 3-25 days after being deposited. After hatching, it takes 1-2 years for a bullfrog tadpole to fully change into a bullfrog. During this time, the tadpole starts to lose its
tail and grow legs. When all four legs are completely grown, the tadpole has fully developed into a frog, and the cycle begins again.
Many people don't realize this at all, the fact that frogs can hear. Before this report I had no idea that these little slimy creatures (a lining of mucus stays around the skin to keep
them moist,) could actually hear because I saw no ears. Later through research I found that they do have small circular patches below and behind each eye called the tympanic
membrane. When some nosy predator (or an inept frog-catcher-wanna-be student) makes a sound, the membranes vibrate, which in turn vibrates the air inside of the ear canal,
then proceeding to vibrate the inner ear which tells the brain that there is a noise being heard. In the event of a predator frogs have many defenses. The bullfrog's legs have many
uses. The hind legs are powerful and used to jump great distances, especially when evading predators (which has been observed by said student too many times). Also, the bullfrog
uses its legs and webbed feet to swim swiftly through the water. In addition to these defenses, a frog may try to play dead so as to discourage any predator trying to catch moving
lunch.
The bullfrog's anatomy has many unique functions that are necessary to its survival. One of them is its respiration system. The frog breathes with its lungs, like most other animals,
but it can also absorb oxygen through the pores in its skin. This allows it to gather extra oxygen when it needs to make quick actions that require a lot of energy. Along with these
are the fact that frogs have a third eyelid, which is transparent, and it allows them to surface with their eyes open, and they can dive with their eyes open. They don't have to worry
about the breaking of the surface-tension on their eyes because it not only acts as goggles, for clarity, but also for protection. Another function is the bullfrog's digestive tract. The
bullfrog can actually depress its eyeballs into the top of its mouth to help force down food. Also, if the food is poisonous, the bullfrog can disgorge its stomach completely out of its
mouth, and scrape the food off with one of its feet. The bullfrog's legs are slightly asymmetrical, so the same foot, the nearest one to the mouth, is always used. The Bullfrog is an
important part of the ecosystem. It serves as a predator to insects, minnows, and other small creatures, as well as a food source to larger predators. Its amphibian nature makes it
flexible to changes in the environment: if food on land starts to become scarce, it can just search for some in the water, and vice-versa. In general, the Bullfrog is a multi-talented
creature containing many bizarre and unique attributes that has convinced us of the value of this species as our subject.
Bullfrog Tadpole
Our Discoveries
We had only one main question at the start of our project, and it was as follows: Do frogs in the Arroyo Del Valle become more active at night, and are they more prone to certain
climates than others? Our Hypothesis was: We think that frogs are nocturnal and are more inclined to stay near the shoreline habitats, as opposed to just land or just water. We
also think that they will become more active at night. Our procedure was at first very simple, it was just to survey the creek and tell about what we had found. We soon found that
it would take much more research and planning to answer our question.
Our major goal was to survey and check how many frogs were showing up at what sites; and then we got curious. During one of our many trips to the creek, we found a site
where there were more frogs than anywhere else in the creek. (Between sites 4 and five.) The frogs were mostly Green frogs, but we kept hearing the giant rumble of the larger
Bull Frog. As we investigated further, we found that these particular frogs did not migrate from site to site. Every time we went down to the creek, the Bull Frog was in "The Den,"
or as we like to call it, site 4 and 1/2. We began to wonder why the frogs preferred this place to other places in the Creek, then it hit us. We observed a dead, fallen tree that had
been stuck in the water, giving any animals the proper protection from natural predators, while giving them a chance to feed, and sun themselves frequently. We soon realized why
this was the prime target for most frogs. We would try to catch the frogs in this place, and it was even still difficult for us to get to them in this protected area. The frogs were smart,
they stayed alive by staying under cover.
We also noticed that the frogs would sit with their heads only above water, floating, waiting. One thing that we surly will never forget is that frogs are definitely one of the most
patient creatures on the earth, (More so than humans, anyway.) They would float, most of the time clinging to sticks, shrubs, or any other debris that kept them from being swept
away by the current. (They stayed in areas where the water was calm, and sometimes shallow. They liked to be next to the shore, (but were often scared away,) because it is
warmer near the shore.) Because these animals were cold-blooded, we found that they enjoyed being warm, because it gave them a greater activity cycle. We also noticed that
while half of them were in the water, and half of them out, there was a distinct change in color between the two, in that one frog could have two different shades of color. This is
because of the fact that the water is a colder temperature than the air around it, and it makes the skin color dull, giving a darker look to it from above the water.
We also noticed that when we got to close to the frogs, and the jumped away for safety reasons, that they made a slight "eep" noise, which we could only guess is to warn any
other frogs for danger. We found out though that it is actually quite common for common bull frogs to scream, or lunge at prey when they feel threatened.
When we came at night to see if the frogs were nocturnal, we got mixed answers. First of all, we heard more of the creatures than we saw, -we saw none- because they were
mostly migrating during the night time. They move at night, just so they can relax in the day, just to call for mates again at night... An endless circle of froggy life.
We were half right about the frogs being nocturnal, in that they croaked, and did their noisy mating calls at night, but they were not as abundant as they were in the day time. We
also found out that their location affects their temperature, which in turn affects their actives, so we were definitely right on there. The warmer they are, the happier they are. They
will in fact migrate at night to a location more suitable for the day time, in which they would prefer to be warm.
We collected a lot of data to be used as study material in the formation of this report. Here are some charts that show our data that was collected.
Conlusion
In conclusion we think that it is important that we do not change the environment because these creatures lives are in direct contact with our own. If we let global warming rise, and
assuming that these above charts stay at the same rate, our town will become over-populated with frogs. This is highly unlikely, but it is important to note the fact that our existence
plays an important role in the victory or demise of certain species.
We found that frogs are a small bit nocturnal, but are generally more interested in moving to a location that promotes their survival and over all well being. We, as humans, must not
allow small things to escalate into bigger problems, such as the over population of frogs in Pleasanton for example. If these creatures have been around for more than 200 million
years, and counting, I think we had better not be the species to screw it up. These creatures survied the demise of the dinosaur, and saw the ice age come and go, but they have
not yet met their fate. It is important that we have projects like these forced onto us so that we may see the importance of our actions, not against one individual animal, but against
a species. I would hate more than anything to see us, the human race, be the downfall of the frog. Now knowing the things we know from doing this project, we feel that we are
much more unlikely to bring about the death and extinction of an entire species.
In the future, if any other groups would be interested in doing further research on our hypothesis, FEEL FREE TO DO SO! We would consider it an honor to have someone
follow up on the work that we have done, but if I could do it all over again, I would catch a specimen, and observe it so as to give my group a better understanding of what these
creatures are about. I would also like to offer some kind words to any person dealing with these stubborn frogs - HAVE PATIENCE! It takes time to get things correct, don't
rush, and next time we would have liked to have found some eggs, but it could be the improper season for that. Other than that, nothing would please us more than to see some
more concerned individuals doing something to educate people about one of nature's greatest gifts,
Bibliography
The books used were:
"Frogs, Frogs, Everywhere" by D.M. Souza (1995)
"A Chorus of Frogs" by Joni Phelps Hunt (1995)
"Encyclopedia Britanica" (1994)
The Online sites which gave us research are as follows::
